Some medical devices may monitor one or more hemodynamic characteristics of a patient, such as the blood oxygen saturation level in arterial blood, the volume of blood supplying a particular tissue site, and the like. Example medical devices that monitor hemodynamic characteristics of a patient include pulse oximeters. One type of pulse oximeter, which may also be referred to as an optical perfusion sensor, includes at least one light source that emits light through a portion of blood-perfused tissue of a patient, and a detector that senses the emitted light that passed through the blood-perfused tissue. An intensity of the light sensed by the detector may be indicative of hemodynamic function of the patient, such as oxygen saturation of blood of the patient.
In some types of optical perfusion sensors, the one or more light sources may be positioned on the same side of the blood perfused tissue as the detector, such that the detector detects light emitted by the light sources and reflected by blood. This type of optical perfusion sensor may be referred to as a reflectance optical perfusion sensor. In other types of optical perfusion sensors, referred to as transmissive perfusion sensors, the one or more light sources may oppose the detector, such that the detector senses light that is transmitted through the blood perfused tissue.